In processing fish, fish are taken from the ocean or fresh water and eviscerated often with filleting. In this process, the fish can become contaminated with certain bacterial or may naturally have such bacteria on the skin. Shellfish is often just cooked and the shell removed.
Bynagte, U.S. Pat. No. 3,705,040, treats shellfish, particularly shrimp, with a solution of water, acid pyrophosphate and tripolyphosphate or metaphosphate or hexametaphosphate or trimetaphosphate or sodium orthophosphate for a period of two minutes followed by cooking at least 2 minutes, cooling and shell removal. The phosphates are thought to make removal of the meat from the shell easier.
Swartz, U.S. Pat. Nos. 3,493,392 and 3,620,767, and Canadian Patent No. 847,280, teaches treating frozen tuna or frozen bonito with phosphate prior to cooking to increase the yield of light meat. The treatment solution is pumped into the fish in much the same way as with hams and the like.
Kohl, et al., U.S. Pat. No. 3,681,091, teaches treating foods, including fish fillet, with 10% solutions of medium chain length polyphosphates.
Other patents teach treating meats with orthophosphates combined with other phosphates and salts to improve taste and texture. For example, U.S. Pat. No. 3,782,975, to Zyss the primal cuts are maintained between 32.degree. F. and 42.degree. F. for about 3 to 5 days. During that period the sodium nitrite reacts with the myoglobin of the meat to form nitrosomyoglobin which insures good color. The addition of the curing solution to the primal cuts imparts improved texture and tenderness that would be lacking if the brine was not added to the meat. Zyss teaches that for people with a sodium problem that a pumping solution of potassium salts including potassium orthophosphate, could be employed.
A second patent to Zyss, U.S. Pat. No. 3,775,543, suggests the addition of potassium phosphate compositions including potassium orthophosphate to processed meats as a binding agent in from 0.2% to 2.0% by weight of the food mix being processed. Zyss clearly avoids alkaline pH since alkaline pH decreases the shelf life. Zyss neutralizes with acid to pH 6.4 to 6.8. In Example II, Zyss prepares a bologna product using about 1% tripotassium orthophosphate.
Ueno, et al., U.S. Pat. No. 4,592,892, uses ethanol to sterilize certain food including various fishes and raw seafood and processing machinery and may employ a carbonate and/or trialkali phosphate combined with the ethanol to enhance the ethanols effectiveness.
Freund, et al., U.S. Pat. No. 2,957,770, teaches improving the properties of meat with a casein composition which can include inorganic orthophosphates such as disodium hydrogen orthophosphate.
Cheng, U.S. Pat. No. 4,683,139, teaches a process for prepackaged fresh meat at retail wherein the shelf life of the meat is increased by treatment with an aqueous solution of an alkali metal salt of certain phosphate compounds, a reducing compound such as ascorbic acid and a sequestering or chelating agent such as citric acid. The phosphate can be an orthophosphate, pyrophosphates, tripolyphosphates and hexametaphosphates and will vary in the way the buffer solution is applied to the meat giving a pH below neutral.
Szczesniak, et al., U.S. Pat. No. 4,075,357, teaches salt combined with a secondary salt selected from alkali metal salts of organic acids and trisodium orthophosphate, polyphosphate, metaphosphate and ultraphosphate. Citrates are preferred combined with sodium chloride. These mixtures are used to control water activity in intermediate moisture cooked food.
Many treatment systems for poultry have been suggested. It has been reported that the thermal death rate of salmonellae can be increased during scalding by elevating the pH of the scald water to pH 9.0.+-.0.2. Agents such as sodium hydroxide, potassium hydroxide, sodium carbonate, and trisodium phosphate have been reported as effective pH adjusting agents for use in increasing the thermal death rate of the bacteria. Trisodium phosphate was reported as least effective in increasing the death rate. See "The Effect on pH Adjustment on the Microbiology of Chicken Scald-tank Water With Particular Reference to the Death Rate of Salmonellae", T. J. Humphrey, et al., Journal of Applied Bacteriology 1981, 51, pp. 517-527.
T. J. Humphrey, et al., have also reviewed the pH effect of scald water on Salmonella on chicken skin. See "The Influence of Scald Water pH on the Death Rates of Salmonella typhimurium and Other Bacteria Attached to Chicken Skin", Journal of Applied Bacteriology 1984, 57 (2), pp. 355-359. Scald water adjusted to pH 9.0.+-.0.2 as in the 1981 paper can help to reduce external and internal cross-contamination of carcasses by salmonella.
"Phosphate and Heat Treatments to Control Salmonella and Reduce Spoilage and Rancidity on Broiler Carcasses", J. E. Thompson, et al., Poultry Science, 1979, 58, 139-143 teach Kena phosphate, a blend of 90% sodium tripolyphosphate and 10% sodium hexametaphosphate, did not consistently or affectively change either salmonella survival or total bacterial count.
Attempts have been made to pasteurize poultry meat by treating the meat with a solution containing agents such as lactic acid, acetic acid, sodium carbonate, sodium borate, sodium chloride, potassium hydroxide, chlorine and EDTA. All treatments, except sodium borate, sodium chloride, and sodium carbonate, reduced the visual acceptability of the meat. Chlorine failed to destroy bacteria on the surface of the poultry but would be expected to control salmonellae in water. See Chemical Pasteurization of Poultry Meat, J. S. Teotia, Disseration Abstracts Intl. B., 1974, 34(a), 4142.
It is known that the shelf life of chicken carcasses can be increased 1 to 2 days by chilling the poultry in a solution of 6% sodium tripolyphosphate/0.7% sodium acid pyrophosphate (Kena--a trademark of Rhone Poulenc, Inc.). See The Antimicrobial Effect of Phosphate With Particular Reference To Food Products, L. L. Hargreaves, et al., The British Food Manufacturing Industries Research Association, Scientific and Technical Surveys, No. 76, April 1972, pp. 1-20 at p. 12. Many patents and articles suggest the use of polyphosphates in preserving meat and fish products.
In addition, it is also stated in the Hargreaves reference at p. 7 that G. Pacheco and V. M. Dias is an article entitled Bacteriolytic Action of Phosphates, Mems Institute Oswaldo Cruz, 52 (2) pp. 405-414, reported on the bacteriolytic action of solutions of monosodium, disodium, trisodium and dipotassium orthophosphates on dead and living cells of Salmonella typhosa, Escherichia coli and Staphylococcus aureus. Trisodium phosphate dodecahydrate is stated to have the greatest lytic action. The reference does not relate to treating meat or fish.
British patent 935,413 teaches treating raw poultry in the chill tank with a non-cyclic polyphosphate. It is taught that this method provides increased preservation of the poultry flesh by decreasing exudate and thereby decreasing spread of bacteria.
Trisodium phosphate has also been found to be effective in inhibiting the growth of blue mold in cuts and bruises in fruit by treating the broken surface with the solution of trisodium phosphate (U.S. Pat. No. 1,774,310).
Trisodium orthophosphate is also a known and widely used anticaking agent (see U.S. Pat. No. 2,770,548).
Trialkali metal orthophosphate has been found by us to effectively reduce salmonella in chicken in application Ser. No. 530,131, now U.S. Pat. No.5,069,922 and also in allowed application Ser. No. 716,260, filed Jun. 7, 1991 (no patent number issued). It is also found to be effective on red meat as disclosed in pending application Ser. Number 712,245, filed Jun. 7, 1991.